Oscillating fluid impeller



Jan. 1939. `s. P. NEMETH A 2,143,024

OSC ILLATING FLUID IMPELLER Filed March 13, 1957 2 Sheets-Sheet l f 14 .Ill!` L .wml l; l2 mur-QW j A/ 1,7 l J2 Patented Jan. 10, 1939 UNITED STATES PATENT oFFicE 4 Claims.

This invention relates to a rotary fluid impeller, having a plurality of substantially radial blades, and intended to impart momentum to a fluid within which it is rotated. The uid, such as air or water, assumes or intensifiesa motion substantially parallel to the axis of rotation.' This fluid motion may itself be the desired effect, as with oice fans or similar blowers or pumps, or again, the reaction to this fluid acceleration that is to say the force exerted by the fiuid on the im-l peller may be the desired effect, as with ship and aircraft propellers, and with the lifting member of rotary type aircraft.

This invention relates more specifically to such impellers in which the individual impeller blades are fastened tothe hub rotatably about their longitudinal and a substantially radial axis. The object of the invention is an increase of the eciency and performance of the impeller. I have discovered that the impeller efficiency is greatly benefited by imparting to the blades short periodic angular oscillations about their longitudinal axes, whereby their pitch angle is periodically varied.

It is accordingly the object of this invention to provide a rotary radial-blade impeller in which the pitch angle of the bla'des is periodically and swifty varied.

It is another object of this invention to provide for such impeller in which all blades oscillate with equal period and in phase, so that all pitch angles reach their maximum and their minimum at the same time.

It is another object of this invention to provide for an impeller with oscillating blades in which the oscillation period is at most equal to one half of the time for one impeller revolution.

It is still another object to provide for such impeller in which the blades have superposed to such before described and predetermined oscillating periodic motion, at the will of the operator, a similar periodic pitch angle variation of variable amplitude, in phase with the revolution of the impeller, and in multi-phase relation with respect to the several blades, either by itself, or together with a constant additional pitch angle change.

These and other desirable objects and advantages of the present invention will be illustrated in the accompanying drawings and described in the specification, certain preferred embodiments being disclosed by way of illustration only, for, since the underlying principles may be incorporated in other specific devices, it is not intended to be limited to the ones here shown, except as such limitations are clearly imposed by the appended claims.

In the drawings, like numerals refer to similar parts throughout the several views, of which Fig. 1 represents a sectional side view of a two-blade oice fan embodying the invention,

Fig. 2 represents the rear view of the same fan, as indicated by the line II--II of Fig. 1,

Fig. 3 represents the cam member I8 of Figs. 1 and 2 in an enlarged scale, and

Fig. 4 represents a schematic view, sectional in part, of the hub section of the lifting member of a rotary aircraft, embodying the invention.

In Figs. 1 and 2, there is shown the housing I0 of an electric motor, its motor shaft II, an impeller hub I2 rigidly mounted on shaft II, arms I3 extending from hub I2, radial bearings I4 in said arms, a pair of impeller blades I5 rotatably held in bearings I4, arms I6 extending from said blades, sliding members I'I on arms I6,`a cam member I8 integral with housing I0, and a cam groove [9 in cam member I8 engagingsliding member I 1. Said groove extends around cam member I8 in a sinuous way, such that through the entire circumference of the cam member the largest distance between the groove and the electric motor, as Well as the smallest distance is each reached two times. That is to say, the groove pattern is doubly repeating.

When the impeller hub I2 is turned by the motor shaft II, sliding members I'I glide within groove I9, turning thereby lever arms I6. These levers turn their respective blades in their bearings I4, whereby a periodic change of the pitch angles of blades I5 is caused, increasing and decreasing the pitch twice during each revolution of the hub. One such complete cycle of changes of the pitch angle with respect to a substantially radial axis coextensive with the principal extension of the blade, whereby the blade occupies each angular position twice, once while in the process of increasing it and once while in the process of decreasing it, isin the following counted as one change or variation of said angle. It is also seen that at all times the pitch angles of the two blades I5 are alike all periodical changes of said angles being in phase with each other, the sliding members I'I engaging always points of groove I9 at equal axial position. That is to say, the variations of the pitch angle of the two blades occur simultaneously.

In Fig. 4, there is no motor, but the impeller is intended to be driven by theair in a wind mill manner. In other respects, the function of the parts is similar. Cam member I8 of Fig. 4, however, is not rigidly fastened, but movably. It is hel-d by screw bolts 20 in screwing engagement with nuts 2 i, which latter are fastened to member I8. Bolts 20 are rotatably mounted on the structural frame 22 of a rotary aircraft, and can be turned independent of each other by the pilot, in any conventional manner. This is schematically indicated by hand cranks 23. Blades I5 are shown to have hinges 24 as is often provided in autogyro aircraft.

If cranks 23 are turned in equal direction, cam member I8 is lifted or lowered, and the pitch angle or blades I5 is thereby increased or decreased by a constant amount, which superposes to the periodic change of that angle produced as described with the oilce fan of Figs. l and 2. Ii the cranks 23 are turned in opposite directions, one clockwise the other counterclockwise, the cam member I8 is tilted, by virtue of which the pitch angle of blades I5 is periodically changed once during each revolution in a manner well known per se. These latter changes of the pitch angles of the several blades do not occur simul taneously, but in staggered time relation, out of phase. This change in direct period with the revolution superposes itself to the constant change, if any, and to the predetermined periodic change of double period, caused by the sinuous groove I9.

I have obtained best efliciencies with a periodic variation of the predetermined kind of the pitch angle by plus minus three degrees.

I claim:

1. A rotary duid impeller comprising a hub, a

plurality of substantially radial blades mounted on said hub rotatable around substantially radial axes, cranks on said blades, sliding members on said cranks, a non-rotatable shiftable and tiltable cam member, and cam groove means around said cam member in operative engagement with said sliding members, adapted to produce oscillations of all blades in phase with each other.

2. A rotary fluid impeller comprising a plurality of substantially radial blades, first means for varying periodically the pitch of said blades, said variations being in phase with each other, and second means for varying periodically and in staggered time relation the pitch angle of said blades once during each impelier revolution.

3. A rotary iuid impeller comprising a hub, a plurality of substantially radial blades mounted on said hub rotatable about substantially radial axes, cranks on said blades, sliding members on said cranks, a non-rotatable cam member, and a sinuous cam groove around said cam member in operative engagement with said sliding members, the pattern of said groove consisting of portions repeating themselves as often as there are blades.

fi. A rotary fluid impeller comprising a hub member, a plurality of substantially radial blades mounted rotatably about substantially radial axes on said hub member and interconnected so that the pitch angles of all blades are alike at all times, and means for oscillating the blades about said radial axes.

STEFFEN P. NEMETH. 

